Sewing machine needle bar operating mechanism



S. ADLER May 29, 1951 Y SEWING MACHINE NEEDLE BAR OPERATING MECHANISMFiled July 18, 1947 fun INVENTOR. 50107120 Heller WM m HTTO/PNEYSPatented May 29, 1951 SEWING MACHINE NEEDLE BAR OPERATING Q a vMECHANISM 7 Solomon Adler, Gardens, N. Y.

Application July 18, 19,47,Serial No. 761,916

This invention relates to needle bar operating mechanism forsewingmachines. This application is a continuation in part of my applicationfor Sewing Machine Needle Bar, filed August 30, 1946, Serial No.693,918. x g

The conventional type ofsewing machine is provided with an eccentric anda gear mechanism therefor to convert the rotary motion of the main driveshaft into the reciprocating movement through which the needle bar mustpass to perform its function in the stitching operation. This kind ofmechanism requires a fly wheel of considerable size to equalize themovements of the eccentric. It is, therefore, little suited for amachine ofsmall overall-dimensions, like, for instance, a portablesewing machine.

aoljaims. (o1.112 221) to the frame 1 in order In this latter type ofmachine a form of needle,

drive is, therefore, desirable which dispenses with the necessity of acrank, eccentric and fiy wheel. Suitably, this can be accomplished bysecuring to the needle bar a follower pin riding in intersecting groovesof a cylindrical cam member. 1 Thus, when the cam member is rotated areciprocating movement will be imparted to the needle bar. However, ifthis form of needle drive is used, difiiculties are liable ,to arisefrom the limited dimensions of the several co-operating parts and anyattempt to provide for a more generous dimensioning of the machine wouldseriously interfere with the general objects of a compact and portabledevice. A particular drawback lies in the tendency of the follower pinto become wedged in the intersecting grooves, or to result in excessivefriction and wear, or otherwise to endanger the proper engagement withthe cam member.

It is an object of the invention to obviate these drawbacks and toprovide in general for a needle bar which, in spite of its smalldimensions, is reliable in performance, simple in construction and freefrom heavy or oversized parts.

My invention will be described in the following specification withreference to the drawings, of which:

Fig. 1 is an elevational view of the needle bar, partly in a verticalsection;

Fig. 2 is a horizontal section through Fig. 1 on lines 2--2; and

Fig. 3 is a fragmentary view of the follower and its bearing.

Referring to the drawings, it will be seen that the needle bar I is ofconventional form and at its lower end carries the needle holder la. Theupper end of the bar extends into a flattened shank 3 which is engagedby a bracket 2 secured to prevent the needle bar from rotating.Pivotally connected to the shank 3 is a lever 4 of the thread take-up.All this is well-known in the art and forms nopart of this invention.

According to my invention, a drum or sleeve 5 is rotatably seated inbearings 6 of the frame I. The drum completely encompasses the needlebar and is provided in its inner face with an endless left and righthandthread, generally indicated at 8. A bevel gear 9 is carried at the upperend of the drum for engagement by a mating gear Ill, which latter gearis disposed on the drive shaft (not shown) by which motion istransmitted to the device. For the vertical movement of the needle bar,the drum is apertured, as shown at l l.

Secured to the needle bar is a follower member l2 .which is adapted toride in the groove of the left and righthand thread of the drum. Thestem I3 of the follower extends into an opening M of the needle bar. Itis undercut to provide a shoulder l5 and a reduced shank portion Hi.There is thus formed an internal recess H in which a compression coilspring I8 is maintained. The shank l6 protrudes rearwardly from theopening and is restrained against excessive forward displacement bydouble retaining and adjustment nuts I 9 which are mounted on thethreads at the free end of the stem.

The follower thus is adapted both for rotational and translationalmovement, the latter being in an axial direction.

The contact face 20 of the follower is bowshaped so as to conform to thecurvature of the thread groove. As shown in Fig. 2, the contact face hasa transversa1 cross-section of considerably greater width than the stem[3. It, thus, is adapted safely to span the gap formed by theintersecting threads.

As indicated at 1|, a clearance adjacent the terminal flange22 of thedrum is provided for the purpose of an unobstructed reversal of thefollower from one to the other thread at the end of each stroke.Obviously, the upper end of the thread which is not visible in thedrawings should be formed in an identical manner.

From the description given it Will be manifest that, when the drum 5 isrotated by means of the drive shaft and intermediate bevel gears 9 and[0, a vertical reciprocating motion is imposed on the needle bar throughthe follower member. Also, it will be appreciated that the severalfeatures embodied in the follower member, to wit, the rotatable seating,the axial movability and the wide contact face, all, contribute ineffecting a yielding engagement between follower and thread. In thismanner, a smooth sliding fit of the follower in the groove is assureddespite the narrow dimensions of the several parts and notwithstandingpossible rough surfacing.

Obviously, many modifications are possible without departing from thespirit of the invention. Therefore, except where otherwise limited bythe claims,*various alternative structures may be employed.

What I claim is:

1. In a sewing machine, a frame, a needle bar, a cylindrical memberencircling a part of said bar, said member being rotatably carried bysaid frame and having a left and righthand thread, means to impart arevolving action to said memher, the axis of revolution being parallelto -the needle bar, an aperture in said needle bar, a follower memberextending through said aperture and being rotatable on its axis andbeing axially movable, spring means maintained between said follower andsaidneedle bar and adapted to urge sai'd follower into contact with saidthread, and an operative connection between said follower and saidneedle bar whereby a reciprocatingmotion' is imparted to the needle barupon revolution of the cylindrical member.

2. In a sewing machine, a frame, a needle bar, a cylindrical memberencircling a part of said bansaid member being rotatably carried by saidframe and having a left and righthand thread, means to impart arevolving action to said member, a follower member rotatable on its axisand axially movable, spring means for urging said follower memberaxially into contact with said thread, the thread terminating at pointsshort of the ends of the cylindrical member in order to permit reversalof direction of the follower at the ends of the strokes, and anoperative connection between the follower and the needle bar whereby areciprocating motion is imparted to the needle bar upon revolution ofthe said cylindrical member.

3. lPna.=sewingimachine, a needlebar, a cylindrical member'surroundingsaid needle bar, a frame, bearings in said frame for rotatably carryingthe cylindrical member, means to revolve said-cylindrical member aboutits longitudinal :axis, the cylindrical member having an internalendless left and righthand thread, an elongated followermember securedto the needle bar, the saidmemberbein'g rotatable about an axisperpendicular to the axis of the needle bar and being axially movable,and means for urging said follower towards said internal thread so as totransmit;a-reciproeatingzaction to the needle bar uponrevolution'ofsaidzfollower member.

SOLOMON ADLER.

REFERENCES CITED The following references are of record in the file-ofthispatent:

UNITED STATES PATENTS Number Name Date Re. 19541 Van Dyke Apr. 16, 19351,020,057 Ringe 1 Mar. 12, 1912 1,373,764 Rooney Apr. 5, 1921 GarciaSept. 3, 1942

